Electric discharge device



Jan. 4, 1938. E, INMAN 2,104,652

ELECTRIC DISCHARGE DEVICE Filed Jan. 25. 1936 2 Sheets-Sheet 1 Inventor": GeorgeE. Inman,

Jan. 4, 1938. 7 2,104,652

ELECTRIC DISCHARGE DEVICE Filed Jan. 25. 1956 2 Sheets-Sheet. 2

Inventor George E. Inman,

H ttornev.

Patented Jan; 4, 1 938 t t a UNITED STATES PATENT. OFFICE ELECTRIC DISCHARGE DEVICE George E. Inman, East Cleveland, Ohio, assignor to General Electric Company, a corporation of New York a Application January 25, 1936, Serial No. 60,848

' 9-Claims. (Cl. 176 122) My invention relatesto electric discharge demetal, such as tungsten, impregnated .with an vices and more particularly to high pressure posielectron emissive material, as described in U. S tive column vapor-arc lamps such as high inpatent application of Eugene Lemmers andHarry tensity mercury arc lamps. M. Fernberger, Serial No..16,614, filed April 16,

The luminous efiiciency of metal vapor are 1935, and assigned to the assignee of the present lamps depends in general on the pressure 01' application. The upper and lowerelectrodes l2, density of metal vapor in the lamp and is infiu- [3 are mounted on lead wires l4, I5 respectively, enced by the loss of heat from the lamp to the the ends of which are coiled around the elecsurrounding atmosphere. Heretofore it has been trodes. The end turn l6 (Fig. 4) is coiled around 10 proposed to enclose the lamps in outer envelopes a reduced end portion H of each electrode, while 10 which were evacuated or filled with gases of low at theother end the lead is bent transversely at heat conductivity so as to minimize the loss of 18 across the end of the electrode, thereby firmly heat and keep the bulb walls as hot as possible. holding said electrode ;,in place. The bulb H. According to my invention, the outer bulb is contains a readily ionizable gas such as argon at preferably filled with a gas of high'heat conlow pressure to assist in starting,,and a vaporiz- 15 ductivity to cool the outer surface of the bulb able metal such as a globule of mercury W. The and permit the use of a higher internal temlamp is preferably designed to operate at a presperature. The used of a cooling gas makes it sure of greater than one atmosphere, preferably possible to have a greater temperature gradient about two atmospheres. The lower end of the. no in the bulb wall, thereby preventing-danger of bulb ll may be coated at l9 (Fig. 2), as with 20 collapse. Thismeans that the pressure and wattplatinum paint,. to increase the heat absorption age may be increased greatly in the samesize and raise the temperature of said lower end bulb. The outer bulb also protects the inner which tends to be the coolest part of the bulb. lamp bulb from atmospheric drafts and the irreg- The lamp I0 is enclosed in an outer glass bulb ularity in bulb wall temperatures caused thereby. or envelope l9 which is preferably provided with The gas probably absorbs more'heat from the hot a stem tube 20 and an exhaust tube 2! through spots of the lamp bulb and therefore tends to which it may be exhausted of air and filled with equalize the bulb wall temperature. gas. The support for the lamp I0 comprises a My invention also includes certain novel feaconductive support 22 bent into a substantially tures in the supporting structure for the inner U or rectangular shaped frame and having its 30 bulb. Further features and advantages of my upper ends sealed in the stem press .23. One invention will appear from the following detailed end of said supportwire 22 is attached to an outer description of species thereof. lead wire 24which is attached to the screw- In the drawings, Fig. 1 is an elevation of one threaded shell 25 of a skirted base 26. The other form of lamp comprising my invention; Fig. 2 is end of said support wire 22 terminates in the 35 a similar view at-right angles to Fig. 1; Fig. 3 is stem press 23. The lower end of the frame 22 is a section taken on the line 3--3 in Fig. 2; Fig. 4 is braced by a substantially semi-circular, preferably a side view, partly in section, of one of the springy, wire 21 located inaplane at right angles electrodes; Fig. 5 is an elevation of a modified to the plane of said frame and engaging the walls form of lamp; Fig. 6 is a sectiontaken on the of the outer bulb ill at its ends. The said wire 21 line 66 in Fig. 5; and Fig. 7 is an elevation of is attached to the lower end of the frame 22 by a another modified lamp. wire 28 welded at its middle to saidframe 22 and Referring to Figs. 1 and 2, the high pressure at its'end to said wire 21. The lower' electrode metal vapor (mercury) arc lamp I0 is of the type lead I5 is welded to the lower end of the frame shown in U. S. patent application Serial No. 8,286, 22 which thus forms one of the current leadsfor filed February 26, 1935, by Eugene Lemmers, and thelamp Ill. The upper electrode lead I4 extends assigned to the assignee of this application. The through an opening in a disc or shield 28 of'rebulb H is of larger diameter at the top than at fractory insulating material and is attached to the bottom, being in this case of substantially a lead wire 30 which extends through the stem 5 oval shape. A pair of electrodes I2, l3 are sealed press 23 to the center contact 3| of the base 26.

in the bulb H, the upper electrode 12 being sub- I The inner or lower end of lead'30 is bent into a stantially adjacent the largest diameter of the transversely extending U-shape against which the bulb while the lower electrode is close to the disc 29 presses,'thereby anchoring the upper end. bottom thereof. The said electrodes [2, |3 may of the lamp ID. The said dis'c 29 is locatedb'e'e. consist of a sintered body of -coarse refractory tween the upper end of the lamp I 0 and the stem soften (e. .g., about 500-800 0.).

press 23, preferably just below the upper end of the frame 22 as shown. The said disc 29 may be provided with diametrically opposite notches 32 (Fig. 3) in which the sides of the frame 22 engage and may be held in place by short wires 33 welded to said frame under the disc.

The outer bulb I 9 contains any suitable gas,

which will absorb heat from the outer surface of the lamp i0 fast enough to keep the walls of its bulb ll below the temperatures at which the glass or other vitreous material of the bulb will The character and quantity of the gas must depend upon the design of the lamp iii. The best efficiency is obtained by keeping the bulb II at a temperature below but as close as safely possible to-the softening temperature of -the glass, that is, overcoollng is to be avoided. Thus, if the construction of a given lamp l0 does not permit of its operation on so high a wattage as to heat its bulb walls to a temperature just below softening,

then the gas used must be correspondingly less in quantity or lowerin thermal conductivity, or both, so as not tocool the bulb wall too much below its softening temperature. v

The preferred gases for use in the outer bulb i9 include hydrogen and helium because oftheir high thermal conductivity. In cases where a filling of helium in the'outer bulb would overcool the inner bulb l3, the helium may bediluted. One flllinglwhich wasfused successfully consisted of a mixture-of-seventy-five per cent helium and twenty-five per cent 'nitrogen, by volume, which has a lower thermal conductivity than helium or hydrogen. At higher than atmospheric pressures gases of poorer heat conductivity, such as air or nitrogen, may be used, especially in cases where helium or hydrogen would over-cool the lamp l9. While the cooling effect increases according to the quantity and pressure of the gas filling, the preferred pressure is about atmospheric. If the bulb I9 is filled at atmospheric pressure when the lamp is cold, the pressure may be around two atmospheres when the lamp is in operation. With the same bulb size, the increasedwattage made possible by the gas filling in bulb 19 may produce an efficiency about ten per cent greater and a light output as much as one hundred per cent greater or more.

in the lamp shown in Fig. 5, the outer bulb l9 and the supporting structure for the lamp ill are the sameas in Fig. 1, the lamp l0 itself,

in this case having a bulb Hand electrodes l2, i3 of different shape and form. The bulb H is in this case cylindrical and the electrodes l2, l3 consist of cylindrical bodies similarto those in Fig. 1 and secured to the leads. I9 and I5 respectively. This lamp i0 is also provided with an auxiliary starting electrode consisting of the 1 end portion 35 of a lead wire36. The other end of lead wire 36 is connectedto one end of a coil of high resistance wire 31 (Fig. 6), such as n'lchrome. The other end of the resistance 31 is connected through a conductor 39 to the frame 22. The lead 36 and conductor are anchored to the disc 29 by eyelets 39. I

In the device shown in 'Fig. 7, the lamp 40 is of the extremely high pressure capillary type disclosed in U. S. patent applicationof Cornelis Bol, Willem Elenbaas, and Hendricus J. Lemmens, Serial No. 46,952, filed October 26, 1935,

and assigned to the assigneeof this application;

The said lamp is mounted transversely of the axis of the outer bulb i9 on rigid leads ll, 42. Up-

wardly extending seal portions 93 at the ends of the lamp 40 are secured to the leads H, 42 by loops of wire 44 weldedto said leads. The lamp 4!! is further supported by several loops of wire 45 welded to a transversely extending end portion 46 of the lead 42. Lead wires 41 extending from the ends of the lamp 40 are secured to the leads I, 92.

The tubular envelope ll of thelamp 49 is of highly heat resistant vitreous material, such as quartz, adapted to withstand very high pressures and temperatures. The envelope 48 contains a pair of electrodes 49 and a small quantity of mercury 50 and a filling of rare gas such as argon or neon at low pressure. A lamp of the proportions shown was operated in the outer gasfilled bulb l9 on alternating current with 8. voltage across the electrodes of about 300 volts and a current of about .6 ampere, the power consumption being about 150 watts. The outer bulb I! was filled'with helium at a pressure of about 600m. H

WhatI claim as new. and desire to secure by Letters Patent of the'United States is: I

1. The combination of an electric discharge lamp comprising a bulb having a pair of electrodes therein, and an outer envelope enclosing said bulb, with a gas content in said outerzenvelope at a pressure inexcess of half an atmosphere, providing enhanced cooling for the inner bulb, as compared with that afforded by direct atmospheric exposure thereof, so that the lamp may operate on .higher current and with higher pressure without heating up the inner bulb wall to its softening temperature.

2. The combination of an electric discharge lamp comprising a bulb having a pair of electrodes therein, and an outer envelope enclosing said bulb, with a quantity of gas confined in said lamp comprising a bulb having a pair of electrodes therein, and .an outer envelope enclosing said bulb, with a quantity of atmospheric gas conlined in said'outer envelope at a pressure in excess of half an atmosphere so as to maintain therein, during normal operation of the lamp, a pressure substantially exceeding atmospheric,

thus providing enchanced cooling for the inner bulb, as compared with that afforded by direct atmospheric exposure thereof, so that the lamp may operate on higher current and with higher pressure without heating up the inner bulb wall to its softening temperature.

4. The combination of 'an electric discharge lamp comprising a bulb having a pair of electrodes therein, and -an outer envelope enclosing said bulb, with a filling of highly heat-conductive gas v v in said outer envelope at a pressure in excess of half an atmosphere'providing enchanced cooling for the inner bulb, as compared with that atforded by direct atmospheric exposure thereof, so that the lamp may operate on higher current and with higher pressure without heating up the inner bulb wall to its softening temperature.

5. The combination of. .an electric discharge lamp comprising abulb having a pair of electrodes therein, and an outer envelope enclosing said bulb, with a quantity of highly heat-conductive gas confined in said outer envelope at a pressure in excess of half an atmosphere so as to maintain therein, during normal operation of the lamp, a pressure substantially exceeding atmospheric, thus providing enhanced cooling for the inner bulb, as compared with that afforded by direct atmospheric exposure thereof, so that the lamp may operate on higher current and with higher pressure without heating up the inner bulb wall to its softening temperature.

6. The combination of a high-pressure. metal vapor arc lamp comprising electrodes axially arranged in an upright bulb containing a charge of vaporizable metal and so proportioned that its walls are heated to approximately uniform temperature by the heat of the are between said electrodes, and an outer envelope enclosing said inner bulb, with a gas content in said outer envelope at a pressure in excess of half an atmosphere providing enchanced cooling for the inner bulb, as compared with that afforded by direct atmospheric exposure thereof, so that the lamp may operate on higher current and with higher metal vapor pressure without heating up the inner bulb wall to its softening temperature.

7. The combination of a high-pressure metal vapor arc lamp comprising electrodes axially arranged in an upright bulb containing a charge of vaporizable metal and so proportioned that its walls are heated to approximately uniform temperature by the heat of the are between said electrodes, and an outer envelope enclosing said inner bulb, with a quantity of gas confined in said outer envelope at a pressure in excess of half an atmosphere to maintain therein, during normal operation of the lamp, a pressure substantially exceeding atmospheric, thus providing enhanced cooling for the inner bulb, as compared with that afforded by direct atmospheric exposure thereof, so that the lamp may operateon higher current and with higher metal vapor pressure without heating up the inner bulb wall to its softening temperature.

8. The combination of a high-pressure metal vapor arc lamp comprising electrodes axially arranged in an upright bulb'containing a charge of vaporizable metal and so proportioned that its walls are heated to approximately uniform temperature by the heat of the are between said'electrodes, and an outer envelope enclosing said inner bulb, with a filling of highly heat-conductive gas in said outer envelope at a pressure in excess of half an atmosphere providing enhanced cooling for the inner bulb, as compared with that afforded by direct atmospheric exposure thereof, so that the lamp may operate on higher current and with higher metal vapor pressure without heating up the inner bulb wall to its softening temperature.

bulb, a disc of refractory insulating material mounted on the upper end of said frame, the lower lead wire of said inner bulb being secured to the lower end of said frame and the upper lead wire extending through an opening in said disc and being sealed in and extending through the upper end of said outer envelope, and a resilient support member secured to the lower end of said frame and extending transversely of the plane of said frame and engaging the walls of said envelope on opposite sides.

GEORGE E. INMAN. 

